sylpheed --version (return code: 0)
Sylpheed version 3.5.1
sylpheed --help (return code: 1)
Usage: sylpheed [OPTIONS ...] [URL]
--compose [mailto URL] open composition window
--attach file1 [file2]...
open composition window with specified files
attached
--receive receive new messages
--receive-all receive new messages of all accounts
--send send all queued messages
--status [folder]... show the total number of messages
--status-full [folder]...
show the status of each folder
--open folderid/msgnum open existing message in a new window
--open <file URL> open an rfc822 message file in a new window
--configdir dirname specify directory which stores configuration files
--dpi dpinum force DPI
--exit exit Sylpheed
--debug debug mode
--safe-mode safe mode
--help display this help and exit
--version output version information and exit